A. Field of Invention
The invention pertains to internal combustion engines and more specifically to a device and methods for limiting the oil pressure generated by an oil pump.
B. Description of the Related Art
Use of oil pumps with a pressure control valve has long been commonly known in the art in internal combustion engines (see DE 12 41 191 A1). For this purpose, provided in the pressure line is a pressure control valve with a spring-loaded valve gate, which, at a predefined oil pressure, creates an opening or a connection to the inlet side of the pump.
Also commonly known in the art (see DE 85 17 900 U1) is the arranging of elements of an oil pump for an internal combustion engine on the camshaft that controls the intake and/or exhaust valves.
The purpose of the present invention is, specifically in the case of an internal combustion engine that is designed as a small engine, in a simple way to limit the oil pressure generated by the oil pump, whereby few additional components as possible are required for the implementation of the oil pressure valve.
The solution of the present invention is achieved through the features which will be described below. The internal combustion engine with the oil pressure limiting valve according to the invention is distinguished by a simple design in which a gradual shutoff flow from the oil pump back into the crankcase is possible in a reliable way by means of the camshaft, which is axially displaceable within the crankcase.
Additional advantageous developments and improvements of the internal combustion engine according to the invention are in the subclaims.
The oil pressure limiting function is achieved in a simple way, in that one face of the oil pump, which is designed as a rotor pump, is sealed off by a spring-loaded sealing washer, which, at a predefined oil pressure generated by the oil pump, opens a defined leakage gap, through which a flow of oil can flow back to the inlet side of the oil pump in order to limit the maximum oil pressure.
Provided between a bearing seat for a bearing journal of the camshaft and a limit stop provided on the camshaft is a spring element that presses the sealing washer against the face of the rotor pump. The side area of one of the cams that controls the intake or exhaust valve can advantageously be provided as the limit stop for the spring element.
The sealing washer for the oil pump is advantageously slipped onto the inner rotor, and lies against a driving gearwheel arranged on the camshaft.
The device itself is made up of few components; for example, the inner rotor of the oil pump is joined with the driving gearwheel for the camshaft as one piece.
An embodiment of the invention is explained in more detail in the following description and drawings.